US1800996A - Wireless signaling system - Google Patents

Description

April 14, 1931. F GERTH ET AL 1,800,996

' WIRELESS S IGNALING SYSTEM .Filed Dec. 21, 1926 @gni g Fw l|n...^.n|\\\h..n| l UWWHUUWHH HHHHmHHHlHn w* Y/Upeflzfe HHIHHHHHHHHI \am'e Mada/@WWW lummuumuu m @wif @i aufefz'de f ii'egzleflfy V45 sired frequencies may pass Patented Apr. 14,y 1931 Y' UNITED STATES PATENT OFFICE FELIX GERTH, F BERLIN-TEMPELHOF, AND FRITZ GUTZMANN, OF BERLIN- v CHARLOTTENBURG, GERMANY WIRELESS SIGNALING SYSTEM Application led December 27,1, 1926, Serial No. 156,095, and in Germany December 24, 1925.

Our invent-ion has reference broadly to Wireless signaling systems and is more particularly intended to provide means for reducing undesired oscillations such as higher i; harmonics or side frequencies and other interferingy frequencies in wireless signa-lingl circuits.

Our invention finds particular application in such cases where disturbing frequencies l are present which are more or less symmetrical to the operatingfor signaling frequency and which are known in the artas side-fre-v quencies. Such frequencies occur especially in systems comprising a high-frequency generatorof afundamental frequency in combination with one or more'iron-cored high-frequency transformers. It has become very well'known in the art of wireless signaling to eliminate undesired oscillations by the employment of intermediary circuits, rejector and acceptorfcircuits, filters and the like.

According to our invention we also make use of the working of rejector and acceptor circuits vand our invention presents a novel V combination thereof inv providing several paths in connection with a signaling circuit, each' path consisting of an acceptor circuit tuned to one of the undesired frequencies andtherefore presenting'zero impedance for this particular frequency and whereby the tuning of the several acceptor circuits is so adjusted that in their resultant action with respect to the operating (signaling) frequency they form' a rejector circuit for the latter and thus' prevent the signaling frequency from entering the by-pass and force 1tback or reject it Vinto circuit portions to be actively employed in the system forsignaling purposes. The effective impedance of 4.6 the by-pass is then increased in value for the particular signaling frequency, whereby the signalingfrequency is confined to the signaling circuit and the by-pass is rendered opaque to the signaling frequency, while the undefreely thru the transparent acceptor circuits constituting the elements .of the rejector circuit arrangement of our invention.

Our invention will be more clearly understood by the following detailed disclosure and specific example in connection with ironcored high-frequency transformer systems reference being taken to the accompanying drawings, in which Fig. 1 is a wiring diagram showing a portion of a signalng circuit with the circuit of our invention associated therewith, and of which Figure 2 is a wiring diagram of an iron-cored frequency transformer system with several circuits of our invention associated therewith, while Figures 3 to 4 inclusive are illustrative curves making clear the working principles underlying the highlfreqFuency signaling system as represented y ig. 2.

Referring more particularly to Figure 1 u of the drawings the invention is shown applied to an antenna ground system indicated by reference characters 1 and 2. Coupling inductance 3 and tunable loading coil 4 are included into this circuit forming the usual tuned oscillatory system. Preceding this antenna circuit is an intermediary circuit composed by coupling inductances 5 and 6, capacity 7 and tuning inductance 8. A coupling inductance 9 imparts to the inter- 75 mediary circuit high-frequency oscillating currents from a generating system of an kind well-known in the art and not indicated in the drawing for simplicitys Sake. VIn the case the circuit relates to a receiving system go the inductance 9 leads to a detector or amplification circuit. Acceptor circuits composed by inductances 10 and 12 and capacitiesll and 13 respectively and being tuned each to one undesired frequency of the' signaling frequency and therefore presenting zero impedance forsame serve as a by-pass to such frequencies. The one acceptor circuit e.'g. 10, 11 then presents a resultant capacitive reactance 14 for the sig- 90 naling frequency and the other 12, 13 a resultant inductive reactancev 15 for same or vice versa, which resultant reactances are indicated in the drawing rby dotted lines. The values of this capacitive and inductive resulting reactances 14 and 15 respectively are dependent of the relation of the capacitive reactances 11 and 13 of the acceptor circuits to their inductive reactances 10 and 12, respectively, as .for the tuning of the acceptor v100 lying at either side 35 Y so chosen and adjusted,

circuits there is only necessary a distinct product of their capacity and inductance (frequency f being equal as is well known to `wherein 'L is the inductance and C the capac-A ity of a tuned circuit) these relationsmaybe reactances "14 and`15 respectively in vrespect to the signaling frequency form in their combined action a rejector circuitl for :this latter forcing it thereby into the portions of the Y circuits system activelyeinployed for signaling e. g. thru coupling coil 5 inthecase of a transmitter or thru coupling coil l6 in the case of a receiver. kThus theA signaling .frequency isprevented from Vpassingin part thru the bypass' circuit, yand losses of the active signaling energy V involved Vby such bypassing are Y eliminated.

Referringnow moreparticularly to Figure 2 of the drawing, similar reference' characters tothat in Figure ments. I transformers .with iron cores 18 and 19 and windings 2O and 21 respectively. The transformer" '16 is energized -by an alternating current source ofa fundamental frequency e. g. a high-frequency generator 22, and the transformer A,17 'forming a second 'transforinationl step is energized bythe first transformer 1 6, the two cascade 'connection whichis generally employe'd when carrying out a very Vhigh-fre- The further elethe system are the I 23 and 24 and they capacities :25' and 26 of the transformeroutqnency transformation. ments vforming part'of tuning self-inductances putlcirciiits respectively 4called alsormultipli- Y cation or impulse Vcircuits as will be understood the following detailed deSCriptionof the working :of the system. Y Y

H'-Ilie'iron-core sty ucture 'of the transformer is given so little iron, that it is already saturise vto free damped osclletiontrains n ,theI

natural frerpaency of the `impulse circuit. 'llhese `oscillation f trains, .because of their Tena successen present a continuous oscillation Lwave such as'represented bythe Fig: ure of the drawings. The oscillations die out tol a; certain extent to be increased to their that the resultant yemployed (e.

Y 1 refer to similar ele-v 16 and 1'? re resent static frecuency` Y P i transformers thus being arranged .inV

(fundamental) .al-pv original value periodically when a new vtension peak occurs. By reducing the damping factor of the impulse circuit to the smallest value possibly by utilizing a small-capacity and a large inductance the dying out of the single Wavetrains .maybe minimizedito such a-n ext-ent ythat an almost sustained .or undamped high-frequency current wave is obtained.u l`However; especially when very "high-frequencies Vare Vto be generated i. e.

when veryYYlarge transformation ratios are g. the seventeenth of a fundamental frequency) no purely sinusoidal os- ,cillationshbut of a shape-more or less ,similar to that represented by Figure 3 will be obtained. Such :a curve according to Fig. 3 equals a modulated higli-frequency current and may therefore be resolved into the .carrier frequency and a number lof frequencies Y lying symmetrically :at :both sides .of same and'known as side-.band frequencies. For

instance an oscillation amplitudevariation or in technical language beingl sinusoidally lmodulated as represented by c in Fig-ure 4l maybe resolved into oscillations of constant Vamplitudes .consisting of the carrier frequency c and quencies b and d lying symmetrically vat both sides ofthe carrier frequency. If the am# pl-itude oftheoscillations does not vary ac-r cording to Aa 1puresine law but according to an irregular'periodical law such as e. g.k is

shown by Figure 3, thisvariation may 'be dissolved at V.its part. according to Fouriers theorem. into a plurality of pure sine variations theresult beingiof the presence of not only one, as in case of Figures, but cfa number` of pairs of symmetrical vside-frequencies. rlhus in signaling systems employingfrequency transformation vapparatus' 'of' the character described, one or more pairs of side frequencies may occur which are `radiated likewise the signaling frequency by a radiating system and may cause interference in the receiving apparatus. By employing circuit arrangements in accordance with our invention these disturbing side-frequencies may be prevented k,from being radiated and thus interference Ydisturbances substantially eliminated. Referring once more toliigigureY 2 yoi-i the one hand and the self-inductance 29 andthe capacity on lthe other hand are so adjusted' that the circuit 27 28 is-tuned to one of a pair of side-frequencies presenting' zero impedance for same and equally circuit 29, 30ris-tuned to the otherside-frequency having sinusoidal side-band fre ies iis the self-inductance 271 and the capacity 28 f ish lying symmetrically with respect tothe sig f nalingv frequency and presenting Yzero iinpedance forsame. :The result is that of only' the lohmic resistance for these. corresponding sideffrequencies remain inv both acceptor circuits 27 28 and 29, 30 respectively."V The whole circuit 27', 28, 29, 30 formsafi'ejector circuit `for the 'signaling frequency, by ad'- f justing a suitable relation of inductance 27 to capacity 28 and inductance 29 to capacity 30 respectively in the same manner as described with reference to Figure l.

The circuit associated in accordance with our invention may also be arranged in a multiple way for the elimination of more pairs of disturbing frequencies or for increasing the effect to be obtained. According to Figure 2 an eliminating circuit arrangement is arranged also in the impulse circuit of the second frequency transformer, 31 and 33 being the inductances and 32 and 34 the capacities of its acceptor circuit elements respectively. placed between the multiplication circuit of the second transformer stage and the antenna system may contain a circuit arrangement according to our invention in conformity with the signaling system represented by Figure l.

We may also provide three or more acceptor circuits by-passing three or more undesired frequencies and forming in their combined action a rejector circuit for the signaling frequency.

When dealing with frequency transforming systems as represented by Figure 2 it is necessary, according to a further object of our invention, to provide an eliminating circuit arrangement already in the first impulse circuit as the side-frequencies existing in this latter would be multiplied by the following transformation step and side-frequencies in the second impulse circuits would be so numerous and so close to the signaling frequency, that not even rejector circuits with the highest selectivity would be able to reduce them to a sufficient degree.

The principle of operation of our invention as pointed out may be employed with any sort of signaling circuits especially those where undesired frequencies may be combined into groups enabling the embodiment of a circuit arrangement according to our invention and while'we have described our invention in certain specific embodiment, it will be understood that we intend no limitations other than are imposed by the scope of the ap ended claims.

aving thus described our invention, what we claim and desire to bey secured by Letters Patent of the United States is:

l. In a wireless signaling system, an ironcored frequency transformer having input and output circuits, means for applying a fundamental frequency to the input circuit of said transformer, means whereby a signaling current whose frequency is a multiple of said fundamental frequency flows in said output circuit, said last means being responsible also for a plurality of currents of undesired side frequencies produced besides said signaling frequency, a signaling circuit connected to said output circuit, a second Also the intermediary circuitv circuit comprising ua plurality ofl acceptor, circuits connected to said output circuit, one a'cceptorcircuit being provided for each of objectionable side frequencies for by-passing these side frequencies from said signaling circuit, said acceptor circuits being so tuned that in their combined action they constitute arejector circuit for the signaling frequency.

2. In a wireless signaling system, a plurality of iron-cored frequency'transformers arranged in cascade connection, each having input and output circuits, means for applying'a. fundamental alternating current to the input vcircuit of one of said frequency transformers, means whereby a signaling current the frequency of which is a multiple of said fundamental frequency flows in said output circuits, there being also produced objectionable side-frequencies which flow in said circuits, circuit arrangementsv associated with said transformer output circuits, each comprising a plurality of acceptor circuits, one for each of a pair of said objectionable side frequencies whereby such objectionable lfrequencies are by-passed from portions of the circuitV carrying the active signaling currents, said acceptor circuits for said side frequencies being so tuned that in their combined action they constitute rejector circuits for the respective active signaling frequencies in said transformer output circuits.

3. In a wireless signaling system, a plurality of iron-cored frequency transformers arranged in cascade connection, each having an input and output circuit, means for applying a fundamental frequency to the input circuit of one of said frequency transformers, a signaling circuit, means whereby signaling and other objectionable frequencies of said fundamental frequency flow in the output circuits of said frequency transformers and a circuit arrangement associated with the output circuit of said first frequency transformer comprising acceptor circuit for each of said objectionable frequencies, whereby said frequencies are by-passed from portions of the circuit that are 1n operative relation with a following active signaling circuit, the tuning conditions of said acceptor circuits being so adjusted that in their combined action they constitute a rejector circuit for the multiplied frequency in the output circuit of said first frequency transformer.

4. In a signaling system, a high frequency generator in which a plurality of objectionable side frequencies occur besides a definite signaling frequency, a signaling circuit connected to said generator, means for suppressing sald side frequencies from sald signaling circuit comprising a plurality of acl" ceptor circuits, one for each of said side frequencies, arranged in by-pass relationship in respect to said signaling circuit, the tuning conditions of said acceptor circuits being so adjusted that in their combined action they ting saidsignaling frequencies.

constitute arej'ector circuit for the signaling frequency and a transmitting Ysystem., connected to said signaling circuiti for transmit- 5. In combination with a high frequency i' generator in which besides the signaling frequency disturbing side frequencies symmetrically to the signaling frequency are generated, a generator circuit, a transmitter circuit connectedV to said generator circuit for trans-l mitting said signaling frequency, means for suppressing said side frequencies from said transmitter circuit comprising a pair of acceptor circuits tuned to a pair of symmetric side frequencies and.- arranged inA by-pass relationship in Vrespect to said transmitter circuit, the tuning conditions of said acceptorV circuits being so adjusted that in their combined/action they constitute a rejector circuit for the signaling frequency and a transmitter circuit connected to said generator circuit for transmitting said frequencies. Y

' 'In testimony whereof We have aiiixed our signatures. s Y

f FELIX. GERTH.

FRITZ GUTZMANN.

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